title: Dopamine induces apoptosis through an oxidation-involved SAPK/JNK activation pathway.
abstract: Dopamine (DA) is a neurotransmitter, but it also exerts a neurotoxic effect under certain pathological conditions, including age-related neurodegeneration such as Parkinson's disease. By using both the 293 cell line and primary neonatal rat postmitotic striatal neuron cultures, we show here that DA induces apoptosis in a time- and concentration-dependent manner. Concomitant with the apoptosis, DA activates the JNK pathway, including increases in JNK activity, phosphorylation of c-Jun, and subsequent increase in c-Jun protein. This DA-induced JNK activation precedes apoptosis and is persistently sustained during the process of apoptosis. Transient expression of a dominant negative mutant SEK1(Lys --> Arg), an upstream kinase of JNK, prevents both DA-induced JNK activation and apoptosis. A dominant negative c-Jun mutant FLAGDelta169 also reduces DA-induced apoptotic cell death. Anti-oxidants N-acetylcysteine and catalase, which serve as scavengers of reactive oxygen species generated by metabolic DA oxidation, effectively block DA-induced JNK activation and subsequent apoptosis. Thus, our data suggest that DA triggers an apoptotic death program through an oxidative stress-involved JNK activation signaling pathway. Given the fact that the anti-oxidative defense system declines during aging, this molecular event may be implicated in the age-related striatal neuronal cell loss and age-related dopaminergic neurodegenerative disorders, such as Parkinson's and Huntington's diseases.
authors.affiliation: Molecular Physiology and Genetics Section, Gerontology Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA. luoyq@helix.nih.gov
authors.forename: Y
authors.initials: Y
authors.lastname: Luo
authors.forename: H
authors.initials: H
authors.lastname: Umegaki
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: R
authors.initials: R
authors.lastname: Abe
authors.forename: G S
authors.initials: GS
authors.lastname: Roth
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000166:cytology; D020928:Mitogen-Activated Protein Kinases; D009474:Neurons / Q000166:cytology; D010084:Oxidation-Reduction; D051381:Rats; D015398:Signal Transduction
chemical_list: D000975:Antioxidants; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D004298:Dopamine